London researchers are testing out the immunity-boosting properties of poop on 20 patients with the deadliest form of skin cancer – and they’re looking for donors willing to drop their drawers for the eyebrow-raising study.

“In this particular case we’re looking at changing how the immune system reacts by transplanting a huge amount of this healthy gut bacteria (in feces) from one person to another,” said Jeremy Burton, a scientist at Lawson Health Research Institute, the medical research arm of London’s hospitals.

The researchers are studying if fecal transplants – planting healthy, microbe-rich poop from a donor into a recipient – will lead to better outcomes for patients with melanoma, an aggressive and potentially deadly skin cancer.

Melanoma can be difficult to treat and doesn’t always respond as well as other cancers to traditional treatments including chemotherapy, said Saman Maleki, a Lawson associate scientist in cancer immunology.

Patients with melanoma may instead be treated with immunotherapy drugs, medication that stimulates the body’s immune system to attack and kill cancer cells. But the treatment is only effective in 40 to 50 per cent of cases.

“It looks like melanoma patients who do respond to immunotherapy, they have a healthy-looking gut microbiome,” Maleki said.

“The idea is to replace their gut microbiome with someone who is healthy then give them immunotherapy.”

The fecal transplants are trying to bolster the recipients’ intestinal microbiome, the concert of beneficial microbes that exist in the gut. Studies have shown the microbiome plays an important role in immune system development and staving off pathogens.

By introducing healthy gut microbes to people who are undergoing immunotherapy for melanoma, researchers are hoping the army of beneficial bacteria will give the patient an upper hand in their cancer fight.

“We know that it’s involved in so many part of human function,” Burton said. “The microbiome area is really taking off as an interest because it really does have some sort of role in many aspects of human health.”

Donor feces is processed in a lab, cleaned, concentrated and put into triple-thick capsules the recipient will take orally. The goal is to get as much of the healthy gut bacteria to colonize in the cancer patient as possible.

After years of preparation, the researchers started the trial in June and are still recruiting new patients from the London Regional Cancer Program at London Health Sciences Centre. The researchers will closely track the study participants and measure their microbiome health and their immunotherapy outcomes.

But the study isn’t possible without fecal donors.

Would-be poop donors are subject to an intensive screening process that not only looks for infectious diseases and bowel parasites, but digs deep into the person’s family history and overall health.

Only one in 50 of the people they screen are eligible to become fecal donors, Burton said.

“We have to be really careful with the people that we take in and use poop from,” Burton said.

Fecal transplantation has been successfully used in London to treat patients fighting recurrent C. difficile, a bacterial infection in the intestines that is commonly acquired in hospitals or long-term care homes.

Though this trial is attempting to boost the effectiveness of immunotherapy treatment for melanoma with poop, Maleki and Burton are confident the concept could translate to other conditions.

“This treatment and other variations of this immune therapy are used on other cancer types,” Burton said. “There’s a lot of opportunity to go beyond melanoma. We’re quite lucky here in London, we have everything we need to do this study.”